U.S. patent number 6,661,550 [Application Number 09/838,891] was granted by the patent office on 2003-12-09 for method of fixing polygon mirror and polygon scanner motor.
This patent grant is currently assigned to Seiko Instruments Inc.. Invention is credited to Kaoru Kaneko, Katsushige Konno, Tetsuo Yamamoto.
United States Patent |
6,661,550 |
Konno , et al. |
December 9, 2003 |
Method of fixing polygon mirror and polygon scanner motor
Abstract
A polygon scanner motor has a polygon mirror having an outer
periphery, a mirror surface for scanning light arranged around the
outer periphery, and a setting hole having an inner periphery. A
rotor has a projection having a plastically deformable edge
portion. The polygon mirror is positioned relative to the rotor so
that the edge portion of the projection is disposed opposite a
surface portion of the inner periphery of the setting hole
proximate a center of the inner periphery in the axial direction
thereof. The edge portion of the projection is plastically deformed
against the surface portion of the inner periphery of the setting
hole to thereby connect the polygon mirror to the rotor.
Inventors: |
Konno; Katsushige (Chiba,
JP), Kaneko; Kaoru (Chiba, JP), Yamamoto;
Tetsuo (Chiba, JP) |
Assignee: |
Seiko Instruments Inc. (Chiba,
JP)
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Family
ID: |
18631631 |
Appl.
No.: |
09/838,891 |
Filed: |
April 20, 2001 |
Foreign Application Priority Data
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Apr 21, 2000 [JP] |
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2000-120890 |
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Current U.S.
Class: |
359/207.8;
359/207.11; 359/216.1 |
Current CPC
Class: |
G02B
26/12 (20130101) |
Current International
Class: |
G02B
26/12 (20060101); G02B 026/08 () |
Field of
Search: |
;359/198,200,212,216,217,218,219,871 ;310/90,90.5,91,67R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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09021974 |
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Jan 1997 |
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JP |
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09230268 |
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Sep 1997 |
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JP |
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Primary Examiner: Robinson; Mark A.
Attorney, Agent or Firm: Adams & White
Claims
What is claimed is:
1. A method of connecting a polygon mirror to a rotor, comprising
the steps of: providing a polygon mirror having around an outer
periphery thereof a mirror surface for scanning light, and a
setting hole having an inner periphery; providing a rotor having a
projection having a plastically deformable edge portion;
positioning the polygon mirror relative to the rotor so that the
edge portion of the projection is disposed opposite a surface
portion corresponding to an approximate center of the inner
periphery of the setting hole in the axial direction of the inner
periphery; and plastically deforming the edge portion of the
projection against the surface portion of the inner periphery of
the setting hole to thereby connect the polygon mirror to the
rotor.
2. A method according to claim 1, wherein the projection of the
rotor comprises a ring-shaped step portion having the deformable
edge portion at an outer peripheral edge thereof.
3. A method according to claim 1, wherein the plastically deforming
step comprises plastically deforming the edge portion of the
projection at a plurality of locations at equal intervals along the
inner periphery of the setting hole.
4. A method according to claim 1, wherein the projection of the
rotor has a recess portion proximate the edge portion; and wherein
the plastically deforming step includes the step of inserting a
caulking jig in the recess portion and plastically deforming the
edge portion of the projection using the caulking jig.
5. A method according to claim 1, wherein the polygon mirror and
the rotor are formed of different metals having substantially the
same coefficient of linear expansion to thereby prevent
disconnection between the polygon mirror and the rotor due to
variations in temperature.
6. A method according to claim 1, wherein the polygon mirror and
the rotor are formed of a same metal to thereby prevent
disconnection between the polygon mirror and the rotor due to
variations in temperature.
7. A method according to claim 1, wherein the surface portion of
the inner periphery of the setting hole is disposed at a position
corresponding to an approximate center of the mirror surface of the
polygon mirror.
8. A polygon scanner motor comprising: a polygon mirror having
around an outer periphery thereof a mirror surface for scanning
light, and a setting hole having an inner periphery and a surface
portion corresponding to an approximate center of the inner
periphery in an axial direction thereof; and a rotor having a
projection having a plastically deformed edge portion bonded to the
surface portion of the setting hole of the polygon mirror.
9. A polygon scanner motor according to claim 8; wherein the
polygon mirror and the rotor are formed of different metals having
substantially the same coefficient of linear expansion to thereby
prevent disconnection between the edge portion of the projection of
the rotor and the surface portion of the setting hole of the
polygon mirror due to variations in temperature.
10. A polygon scanner motor according to claim 8; wherein the
polygon mirror and the rotor are formed of a same metal to thereby
prevent disconnection between the edge portion of the projection
the rotor and the surface portion of the setting hole of the
polygon mirror due to variations in temperature.
11. A polygon scanner motor according to claim 8; wherein the
plastically deformed edge portion comprises a plurality of
plastically deformed portions bonded to the surface portion of the
setting hole along the inner periphery thereof.
12. A polygon scanner motor according to claim 11; wherein the
plastically deformed portions are bonded to the surface portion of
the setting hole at equal intervals along the inner periphery
thereof.
13. A polygon scanner according to claim 11; wherein the mirror
surf ace comprises a plurality of mirror surfaces disposed around
the outer periphery of the polygon mirror; and wherein each of the
plastically deformed portions of the projection is disposed at a
position corresponding to an approximate center of a respective one
of the mirror surf aces of the polygon mirror.
14. A polygon scanner according to claim 8; wherein the projection
of the rotor has a first portion having a first diameter and a
second portion having a second diameter greater than the first
diameter, and wherein the edge portion of the projection extends
from the first portion.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of fixing a polygon
mirror used for scanning laser beam in a laser beam printer or a
digital copier to a side of a rotating member of a motor and a
polygon scanner motor using the fixing method.
2. Description of the Related Art
In an optical system such as a laser beam printer or a digital
copier, there is used a polygon scanner motor as means for scanning
laser beam. A polygon scanner motor of this kind is constituted by
fixing a polygon mirror which is formed as a polygonal member in a
shape of a thin plate comprising a material of, for example,
aluminum and a side face of which is formed by a light reflecting
face having mirror face accuracy of submicron order, to a rotor of
a motor and is constituted to scan laser beam by making laser beam
impinge to the light reflecting face of the side face of the
polygon mirror in a state in which the motor is rotated at high
speed.
Therefore, according to the conventional polygon scanner motor of
this kind, it is necessary to firmly fix the polygon mirror to a
rotor rotatably provided to a shaft of a stator via a bearing.
Therefore, conventionally, as a method of fixing the polygon
mirror, there are used a method of fixing thereof by an adhering
agent, a method of fixing thereof by bringing the polygon mirror
into press contact with the rotor by a clamp spring and a method of
fixing the polygon mirror by plastically deforming portions of the
rotor to thereby fixedly calk to the polygon mirror.
Among the conventional methods, the method of fixing the polygon
mirror by an adhering agent, poses a problem that time is taken for
curing the adhering agent, a long period of time is taken for
reaching predetermined fixing strength and accordingly, assembly
cost is increased. Meanwhile, the method of fixing the polygon
mirror by using the clamp spring poses a problem that the number of
parts is increased and accordingly, the costs are ncreased,
further, when the polygon mirror is used at high speed rotation of,
for example, 50,000 rpm or more, press force by the clamp spring
must be increased considerably and there is produced a deformation
causing a drawback in scanning light to the reflecting face of the
polygon mirror.
Further, when a flange member of a rotating member is fitted to an
attaching hole of a polygon mirror, an outer peripheral edge of the
flange member is plastically deformed outwardly to be brought into
press contact with an inner peripheral edge of the attaching hole
of the polygon mirror to thereby achieve bonding of the rotating
member and the polygon mirror as is disclosed in, for example,
Japanese Patent Laid-Open No. 230268/1997, there poses a problem
that there is operated force in a direction of bringing the polygon
mirror into press contact with the rotor by calking, thereby,
attitude of the polygon mirror is deviated from required attitude
relative to the rotor, rotational balance is deteriorated and
emittance of noise is caused.
Further, according to such a calking method, large calking force is
needed for fixing the polygon mirror, there is operated force
directed in a direction inclined to the polygon mirror at the
peripheral edge portion of the attaching hole of the polygon
mirror. Accordingly, strain is caused at the light reflecting face
formed at the side face of the polygon mirror with great accuracy,
its flatness is deteriorated and scanning of laser bream cannot be
accomplished with great accuracy. As a result, there poses other
problem that quality of scanning is deteriorated.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method of fixing a
polygon mirror and a polygon scanner motor capable of resolving the
above-described problem in the conventional technology.
In order to resolve the above-described problem according to an
aspect of the invention, there is provided a method of fixing a
polygon mirror which is a method of fixing the polygon mirror by
fitting an attaching hole of the polygon mirror having a reflecting
face for scanning light at a side face thereof to a projected
portion provided at a rotor of a motor wherein a fitting face end
edge of the projected portion is arranged to be opposed to a
vicinity of a center in an axial direction of an inner peripheral
face of the attaching hole and a portion of the fitting face end
edge is subjected to plastic deformation in an outer direction to
thereby fix the polygon mirror to the rotor.
The fitting face end edge can be an outer peripheral end edge of a
stepped recess portion in a ring-like shape formed at an outer
peripheral face of the projected portion.
The polygon mirror and the rotor enable to bond by producing the
plastic deformation simultaneously at a plurality of locations at
equal angular intervals along the fitting face end edge.
A recess is provided previously at the location of producing the
plastic deformation and the plastic deformation enables to produce
by bringing a calking jig in press contact with inside of the
recess. Further, the portion of producing the plastic deformation
is made to be able to correspond to an angle portion of the side
face of the polygon mirror.
Further, the polygon mirror and the rotor are constituted by metal
materials having linear expansion coefficients substantially equal
to each other to thereby enable to prevent a state of bonding the
polygon mirror and the rotor from being changed by a change in
temperature. The polygon mirror and the rotor can be constituted by
the same metal material.
According to another aspect of the invention, there is provided a
polygon scanner motor which is a polygon scanner motor constituted
by fitting and fixing an attaching hole of a polygon mirror formed
with reflecting faces for scanning light at side faces thereof to a
projected portion provided at a rotor of a motor wherein the
projected portion includes a fitting face end edge opposed to a
vicinity of a center in an axial direction of an inner peripheral
face of the attaching hole of the polygon mirror and the projected
portion is formed with plastically deformed portions bonded with
the polygon mirror by pressing the inner peripheral face of the
attaching hole to an outer side thereof in a diameter direction at
a plurality of locations along the fitting face end edge.
Portions of forming the plastically deformed portions can be
provided at equal angular intervals along a peripheral direction of
the projected portion.
The fitting face end edge is made to enable to be opposed to the
vicinity of the center in the axial direction of the inner
peripheral face of the attaching hole by providing a small diameter
portion at an upper end of the projected portion.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a vertical sectional view showing an example of
embodiments of a polygon scanner motor according to the
invention;
FIG. 2 is an essential portion enlarging sectional view for
enlarging to show essential portions of the polygon scanner motor
shown in FIG. 1;
FIG. 3 is an explanatory view for explaining a calk bonding step at
a plastically deformed portion shown in FIG. 1;
FIG. 4 is an enlarged detail view for enlarging to show a state in
which a polygon mirror shown in FIG. 1 is bonded to a projected
portion in a ring-like shape by calking by a plastically deformed
portion in details;
FIG. 5 is a plane view showing calk-bonded portions shown in FIG.
1; and
FIG. 6 is a plane view showing an embodiment according to the
invention when a polygon mirror in a dodecagonal shape is used.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A detailed explanation will be given of an example of embodiments
of the invention in reference to the drawings as follows.
FIG. 1 is a vertical sectional view showing an example of
embodiments of a polygon scanner motor according to the invention,
FIG. 2 is an essential portion enlarging sectional view for
enlarging to show essential portions thereof and according to the
embodiment, there is shown an example of a polygon scanner motor
used for a laser beam printer.
In reference to FIG. 1 and FIG. 2, a polygon scanner motor 1 is
constituted to drive to rotate a polygon mirror 3 by a direct
current motor 2 of a brushless type and the direct current motor 2
is fixed to a base member 4.
The direct current motor 2 is constituted to provide a stator
portion 23 constituted by fixedly adhering a winding coil 22 to a
stator 21 fixed to the base member 4 by pertinent means and a rotor
portion 25 axially supported rotatably by a shaft portion 24
integrally formed to the stator 21 via an air-dynamic bearing
5.
The rotor portion 25 is constituted by fixing a magnet 27 in a
ring-like shape to an inner side of a skirt portion 26A comprising
a magnetic material fixed to an outer periphery of a rotor 26 and
is constituted such that the rotor 26 is rotated by force operated
between a magnetic field by drive current which is made to flow in
the winding coil 22 and a magnetic field by a magnet 27. In this
case, notation 28 designates a thrust plate which becomes a
constituent element of the air-dynamic bearing 5.
The polygon mirror 3 is a hexagonal portion in a shape of a thin
plate comprising aluminum and a central portion thereof is formed
with an attaching hole 31 in a circular shape. Further, at a side
face of the polygon mirror 3, there is formed reflecting faces 32
each having a mirror face accuracy of submicron order for
reflecting laser beam.
The rotor 26 is integrally formed with a projected portion 6 in a
ring-like shape fitted to the attaching hole 31 for fixing the
polygon mirror 3 to the rotor 26 by using the attaching hole 31.
According to the embodiment, there are coaxially formed a large
diameter portion 61 having an outer diameter dimension
substantially in correspondence with the attaching hole 31 and a
small diameter portion 62 integrally continuous to the large
diameter portion 61 and an outer peripheral face of the large
diameter portion 61 constitutes a fitting face 61A for fitting to
the attaching hole 31. That is, the small diameter portion 62 is
formed by providing a stepped recess portion in a ring-like shape
at the outer peripheral face of the large diameter portion 61.
The small diameter portion 62 is provided to enable a fitting face
end edge 61Aa of a fitting face 61A to be opposed to a vicinity of
a center in an axial line direction of an inner peripheral face 31A
of the attaching hole 31, when the polygon mirror 3 is fitted to
the rotor 26 to constitute a predetermined attaching state shown in
FIG. 1.
Further, the large diameter portion 61 is formed with a plurality
of plastically deformed portions 71 constituted by pressing the
inner peripheral face 31A of the attaching hole 31 to an outer side
in the diameter direction at a plurality of locations along the
fitting face end edge 61Aa for bonding the polygon mirror 3 and the
projected portion 6. In this case, both of the polygon mirror 3 and
the rotor 26 are made of aluminum. Therefore, the linear expansion
coefficients of the both members are equal to each other and
therefore, a state of bonding the both members is not changed by a
change in temperature. Further, there may be constructed a
constitution in which the polygon mirror 3 and the rotor 26 are
made of pertinent metal materials having substantially equal linear
expansion coefficient, thereby, the state of bonding the both
members is not changed by a change in temperature.
According to the embodiment, as shown by FIG. 3, the plastically
deformed portion 71 can be produced by pressing a front end portion
101 of a calking jig 100 into a recess portion 7 previously
provided at an upper face 61B of the large diameter portion 61 from
above and deforming a corresponding peripheral edge portion of the
recess portion 7 to a side of the polygon mirror 3 by a taper face
101A of the front end portion 101.
FIG. 4 shows, in details, to enlarge a state in which the polygon
mirror 3 is bonded to the projected portion 6 in the ring-like
shape by calking by the plastically deformed portion 71. According
to the method, when calking operation is carried out by using the
calking jig, the front end portion 101 of the calking jig is firmly
brought into the predetermined recess portion 7 to thereby enable
to form the predetermined plastically deformed portion 71 at a
predetermined portion and accordingly, high quality bonding can be
carried out.
Further, although in FIG. 3, there is shown only a single one of
the front end portion 101 of the calking jig 100, the calking jig
100 is provided with a plurality of the front end portions 101 to
be able to be opposed to a plurality of the recess portions 7
previously provided at the large diameter portion 61 at equal
angular intervals simultaneously and the above-described calking
operation can be carried out by simultaneously pressing the
plurality of front end portions 101 into the corresponding recess
portions 7. Thereby, there are simultaneously formed the plurality
of plastically deformed portions 71 for bonding, which are formed
along the fitting face end edge 61Aa and the polygon mirrors 3 can
be bonded to the projected portion 6 coaxially with the large
diameter portion 61.
As shown by FIG. 5, according to the embodiment, six of the
plastically deformed portions 71 are provided at equal angular
intervals along the fitting face end edge 61Aa, however, the number
of the plastically deformed portions 71 is not limited to six but
the number can be a pertinent arbitrary number regardless of the
number of angles of the polygon mirror 3.
For example, as shown by FIG. 6 in the case of a polygon mirror 3'
having a dodecagonal shape, the calking locations may be disposed
at six locations by providing six of plastically deformed portions
71'.
Further, although according to the embodiments shown by FIG. 5 and
FIG. 6, in both of the embodiments, the calking portions are set to
positions in correspondence with centers of the respective
reflecting faces of the polygon mirror, the calking portions may
correspond to respective boundary portions of the respective
reflecting faces or can be disposed at other pertinent arbitrary
positions.
The reason is that according to the calking method by the
invention, the substantial center in the axial line direction of
the inner peripheral face 31A of the attaching hole 31 of the
polygon mirrors 3, are pressed toward the outer side in the
diameter direction of the polygon mirror 3 by the plastically
deformed portions 71 to thereby achieve bonding of the polygon
mirror 3 and the projected portion 6 and accordingly, not only
small calking force is sufficient but also strain caused at the
reflecting face 32 having the mirror face accuracy of submicron
order by calking, is small and accordingly, the necessity of
particularly selecting a specific portion for reducing the strain
caused at the reflective face 32, is low.
According to the invention, as described above, bonding between the
polygon mirror and the projected portion is achieved by pressing
the substantial center in the axial line direction of the inner
peripheral face of the attaching hole of the polygon mirror toward
the outer side in the diameter direction of the polygon mirror by
the plastically deformed portions and accordingly, not only small
calking force is sufficient but also the strain caused at the
reflecting face having the mirror face accuracy of submicron order
by calking is small and therefore, it is not necessary to select a
specific location to reduce the strain caused at the reflecting
face.
As a result, it is not necessary to provide strain escaping grooves
at the polygon mirror and accordingly, a reduction in cost can be
achieved. Further, since it is not necessary to fabricate grooves
at the polygon mirror, the mechanical strength of the polygon
mirror may not be reduced, further, when the mechanical strength
needs not to be high, thinning formation can be achieved.
Further, since the calking portions can arbitrarily be selected,
calking can be carried out regardless of a number of faces of the
polygon mirror and a reduction in a number of steps can be
expected.
* * * * *